[Feature Request] Add Curve Router as an aggregator

[akshatmittal]

Basically title. Request to add @curvefi/api router to Llama Swap.

Why?

• Adds ability to directly route to/from Curve Pools
• Most aggregators are terrible at routing through all Curve pools, so this should be significantly more accurate for Curve-only tokens.
• (Mostly) Cheaper than other aggregators when using the same route.